package com.future.direction.ui.widget;

import android.content.Context;
import android.graphics.PointF;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.LinearSmoothScroller;
import android.support.v7.widget.RecyclerView;
import android.util.DisplayMetrics;

/**
 * Created by zhp on 2019/5/8
 */
public class ScrollSpeedLinearLayoutManger extends LinearLayoutManager {
    private float MILLISECONDS_PER_INCH = 0.03f;
    private Context contxt;

    public ScrollSpeedLinearLayoutManger(Context context) {
        super(context);
        this.contxt = context;
    }

    public ScrollSpeedLinearLayoutManger(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
        this.contxt = context;
    }

    @Override
    public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position) {
        LinearSmoothScroller linearSmoothScroller = new LinearSmoothScroller(recyclerView.getContext()) {


            @Override
            public PointF computeScrollVectorForPosition(int targetPosition) {
                return ScrollSpeedLinearLayoutManger.this.computeScrollVectorForPosition(targetPosition);
            }//This returns the milliseconds it takes to//scroll one pixel.

            @Override
            protected float calculateSpeedPerPixel(DisplayMetrics displayMetrics) {
                setSpeedSlow();
                return MILLISECONDS_PER_INCH / displayMetrics.density;
                // return 700;//返回滑动一个pixel需要多少毫秒
            }
        };
        linearSmoothScroller.setTargetPosition(position);
        startSmoothScroll(linearSmoothScroller);
    }

    public void setSpeedSlow() {
        //自己在这里用density去乘，希望不同分辨率设备上滑动速度相同//0.3f是自己估摸的一个值，可以根据不同需求自己修改
        MILLISECONDS_PER_INCH = contxt.getResources().getDisplayMetrics().density * 3f;
    }

    public void setSpeedFast() {
        MILLISECONDS_PER_INCH = contxt.getResources().getDisplayMetrics().density * 0.03f;
    }
}


